Christopher Eubanks returns a shot to Borna Coric of Croatia during the Miami Open at Hard Rock Stadium on March 25, 2023 in Miami Gardens, Florida. AFP
Eubanks pulled off the biggest win of his career so far to beat 17th-ranked Croatian Borna Coric 6-3, 4-6, 6-2 while McDonald beat Italy's Matteo Berrettini 7-6 (10/8), 7-6 (7/5).
The 26-year-old Eubanks, ranked 119th in the world, recovered from a first set where the Croat looked in firm control to delight the home crowd.
"I honestly felt like I wasn't playing that bad. I just wasn't executing," Eubanks said. "I felt like my game plan was right. I wanted to be disruptive. I wanted to get the net. I just wasn't executing on shots. I can kind of live with that.
"So I said, 'Well, I feel like I'm playing the right way. If I just continue to try it, hopefully the execution errors will lessen and I'll be able to find my range.' I was able to do that."
Eubanks has been working his way up the rankings as he looks to join an increasingly impressive field of emerging American talents.
The Atlanta native was mentored by former top-40 American Donald Young, who took the 15-year-old Eubanks on the road with him as a practice partner, giving him valuable insight into life on tour.
McDonald won a thriller against 23rd-ranked Berrettini, edging both tie-breaks and surviving two set points in the 12th game of the second set.
Czech Jiri Lehecka's impressive form continued as he took out 18th seed Lorenzo Musetti.
The 21-year-old, who reached his first Grand Slam quarter-final in Australia, triumphed 6-4, 6-4 to reach the third round of a Masters 1000 event for the first time.
Two-time Grand Slam runner-up Stefanos Tsitsipas advanced into the third round after France's Richard Gasquet withdrew with an ankle injury.
Greek number two seed Tsitsipas, will next face Chile's Cristian Garin, who beat Argentine Sebastian Baez 7-6 (7/2), 6-3.
Tsitsipas was runner-up at this year's Australian Open and 2021's French Open but lost his opening round match at Indian Wells earlier this month.
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